The present invention relates to the field of medical imaging. It finds particular application to the acquisition of time of flight (TOF) positron emission tomography (PET) scans, and will be described with particular reference thereto. The invention is also applicable to single photon emission computed tomography (SPECT), and PET as well as other imaging modalities.
Typically, in nuclear imaging, a subject is imaged in axial slices that combine to form a 3D representation of a region of interest. This region could be localized, such as the brain or heart, but it is also typical to perform full body PET scans. Some PET scanners utilize a step and shoot method of data collection, typically utilizing a data acquisition window of about 10 cm wide. Typically, data is collected in a given bed position in frame mode and are transferred so that they are available for reconstruction only after all of the events for a given bed position have been collected. Some Pet scanners move the bed continuously and collect the events in list mode, the events stored first in a buffer and then, after one or several buffers are full, are stored to a disc. Reconstruction then begins after all the data collection has been completed. Specifically, the data is sorted to find substantially redundant rays which are summed and reconstructed in a common operation.
Both of the present methods cause a delay before the reconstruction can begin. Resultantly, images are completed after they would have been had reconstruction began soon after data collection. Reconstruction does not begin until at least after the first region has left the data acquisition window in the step and shoot mode. When the data is reconstructed in sections as separate images, interface discontinuities or artifacts commonly occur. All the data has to be collected in a continuous bed movement scan before reconstruction can start as it is currently implemented. As it stands currently, there is always some delay between the stait of data acquisition and the start of reconstruction.
The present application contemplates a new and improved nuclear imaging apparatus and accompanying method that overcome the above-referenced problems and others.